Collaboration Pays Off with Stunning Performance Metrics
by Nancy Malone, LEED Fellow
|Photo: Siegel & Strain Architects|
This past May, Siegel & Strain celebrated the dedication of the Jess S. Jackson Sustainable Winery Building (JSWB) at UC Davis. And now we are celebrating again, this time for great energy monitoring outcomes!
The JSWB is designed to operate passively and to provide support services, such as electricity production, water filtration and carbon sequestration to the adjacent winery. Our design task was to deliver a passive, net-zero building: the building stays within tightly defined temperature limits without heating and cooling, and generates more electrical energy than it consumes. And based on data collected to date, we are on track to achieve this AND a Living Building Challenge Net Zero Energy certification in about one year’s time.
The main strategy behind achieving net zero energy was to create a completely unplugged (from building systems) and passive building – not easy in Davis’ hot climate, which regularly reaches summer temperatures of 100º F or more – by taking advantage of a diurnal temperature swing of as much as 40º. Our primary strategies include:
• super-insulated building envelope (R-56 walls, R-70 roof)
• a very tight building envelope (blower door test result of 1,950cfm @ 50 Pascals)
• thermal mass in a slab-on-grade floor and an 8’ high CMU wall
• shading of windows and east and west elevations
• night time ventilation
|JSWB appears in the upper left with six new water tanks in place. Photo: UC Davis|
|Photo: Jasper Sanidad|
Passive buildings are never, by their nature, of one gesture or by one author. Rather, they require integrated sets of strategies and a circular, feedback-driven design process across disciplines. And so it is here. We worked closely with a great team to develop and refine the design strategies and were able to repeatedly justify our design decisions – internally and for the client group.
The project is a design/build effort led by Siegel & Strain Architects/Pankow Builders, with design team members Guttmann & Blavoet (G&B), Ingraham DeJesse Associates (IDA) and Cunningham Engineering. Together, we adjusted the design through a series of collaborative meetings and no less than 60 runs of the energy model, constantly evaluating performance relative to construction cost. This level of design iteration is essential for high performance buildings. And to be mainstream, high performance buildings must be cost effective. At one point in the design process we were still 5º F away from our targeted performance point, and we knew that adding thermal mass would get us closer to our goal. G&B calculated how much mass we needed through energy modeling; IDA figured out how tall a CMU wall could be before needing to drastically change the reinforcing or footing. By evaluating the strategy together, we landed on the most cost effective means of achieving our goal.
And the additional design effort has paid off. Several weeks of monitoring during the hottest summer months show that the building is performing right on target: while outside temperatures swing about 40º F each day, the building stays within a narrow band of approximately 5º F. And that feels really good, both from within the building, but also from where I sit reading the data.